1. Field of the Invention
The present invention relates to a contact unit and a printed circuit board connector including multiple contact units.
2. Description of the Related Art
A communication system adopts a differential transmission system for data transmission in a high frequency range of 3 GHz or above, for example. A printed circuit board connector for electrically connecting printed circuit boards such as a motherboard and a daughterboard, for example, has been put into practical use in a transmission path which adopts the differential transmission system. As one of such printed circuit board connectors, a high-speed transmission connector is proposed as disclosed in Japanese Patent Application Laid-Open No. 2010-73436, for example. The proposed structure of the high-speed transmission connector is that a ground contact terminal is each placed between pairs of transmission contact terminals arranged on one of surfaces of a transmission blade that constitutes part of each blade type contact unit. Herewith, this structure prevents crosstalk between signal transmission paths within the common contact unit. Moreover, Japanese Patent Application Laid-Open No. 2010-73436 also proposes a structure in which multiple ground contact plates arranged on the other surface of the transmission blade each have a shield piece integrated with a joining portion. Hereby, this structure suppresses crosstalk between signal transmission paths of the adjacent contact units.
Further, as disclosed in Japanese Patent Application Laid-Open No. 2010-73641, for example, a structure of a ground plate in each transmission blade (which is referred to as a blade in Japanese Patent Application Laid-Open No. 2010-73641) is proposed in order to improve a high-speed transmission performance of a printed circuit board connector. Namely, there is proposed a structure in which one ground plate provided on one of surfaces of a transmission blade has multiple ground pieces arranged in a line at given intervals and corresponding to each of ground terminals arranged on the other surface of the transmission blade (see FIG. 3 in Japanese Patent Application Laid-Open No. 2010-73641). The ground pieces are formed integrally with the ground plate by press work such that tip ends of the ground pieces come into elastic contact with a flat surface of the ground terminal.